Of a semiconductor module for electric power which converts electric power, high efficiency is required from the viewpoint of energy saving.
Because of that, as for a semiconductor element, progressing is a transition from an insulating gate-type bipolar transistor (IGBT) to a transistor, using a wide-band-gap-system semiconductor element (SiC or GaN) for electric power. Particularly, an insulating gate-type transistor using silicon carbide (SiC), which is of high voltage-resistance and able to realize low-temperature resistance, is capable of carrying out high-speed operation for the reason of its being a unipolar-type device, and practical use is expected.
For heat generation of the module during the operation, the heat generation from the semiconductor element occupies most of it. What is by the conduction loss of heat generation carried out when electric current flows in the device, and what is by the switching loss which is generated at the time of switching on the occasion of transit of the device from an ON state to an OFF state or from an OFF state to an ON state occupy most portions of the heat generation from the semiconductor element.
As having been described earlier, in case a semiconductor element for electric power which is configured with a wide-band-gap-system material is used, then high-frequency operation with the same loss becomes capable of being carried out since the switching loss is able to be drastically reduced. As a result thereof, the size of a reactor or a capacitance is able to be made small, and the electric power converting apparatus is able to be configured small. Therefore, because the volume of the inverter itself is able to be drastically reduced, since miniaturization and integration of the configuration of the apparatus itself becomes capable of being carried out, they are being expected.
At this point, in order to realize high-speed operationalization of the device, reduction of the inductance from the electric source side of the smoothing condenser to the ground side through each module phase becomes an important factor. If this inductance value becomes large, accompanying electric voltage heightening of the electric source electric voltage, electric current enlarging and speed heightening of the device, then it becomes a bad influence on the device. Specifically, a through electric current becomes a problem at the ON time and a jumping electric voltage at the OFF time, which, in the worst case, leads to destruction of an element.
Particularly, in a configuration in which plural chips are mounted, accompanying electric current enlarging, the electric current enlarging and the inductance value become in a contrary relation since the package size becomes large.
In Japanese Patent Application Publication No. 2004-22960, in order that the module realizes a low inductance on the occasion when plural semiconductor chips for electric power have been installed, a conventional art is disclosed.
In FIG. 10, a plan view of a conventional semiconductor module for electric power is shown, according to Japanese Patent Application Publication No. 2004-22960.
In this semiconductor module for electric power, adopted is an arrangement such that chips are lined in parallel inside the arm in order to carry out electric current enlarging, the busbars are arranged at the center, and the configuration is allowed to be such that the high-side side element group 73 and the low-side side element group 74 sandwich the busbars.
By arranging that the positive-electrode side inner-part-electrode 71 of the busbar and the negative-electrode side inner-part-electrode 72 of the busbar face each other and adopting a configuration such that the electric currents of each other flow in reverse orientations, a reducing effect of the inductance is being contemplated.
Like this, in the conventional semiconductor module for electric power, utilizing a principle (an effect of mutual inductance) that the busbars in which the electric currents flow in reverse orientations are arranged nearby so that the magnetic fields thereby cancel each other, inductance lowering is thereby being contemplated.